Azomethine pigments

ABSTRACT

Copper complexes of substituted 2,2&#39;&#39;-dihydroxyphenylnapthylazomethines are prepared by reacting the products of o-hydroxynaphthaldehydes and o-aminophenols with a coppering agent. Said compounds are pigments for organic materials.

United States Patent Inman et al.

[4 1 Oct. 24, 1972 154] AZOMETHINE PIGMENTS [72] Inventors: Eric RichardInman, Bridge of Weir, Renfrewshire; Ian Alexander MacPherson, Paisley;John Andrew Stirling, Glasgow, all of Scotland [73] Assignee: Ciba-GeigyAG, Basel, Switzerland [22] Filed: May 20, 1970 [21] Appl. No.: 39,163

[52] US. Cl ..260/438.1, 106/288 Q, 106/309, 241/30, 260/41 C [51] Int.Cl. ..C07f 11/00 [58] Field of Search ..260/438.l; 106/288 Q, 309

[56] References Cited UNITED STATES PATENTS 5/1938 Schmidt ..260/438.l X4/1941 Krzikalla et al.....260/438.I X

2,282,936 5/1942 Chenicek ..260/438.l X 2,442,200 5/1948 Downing..260/438.1 X 3,440,254 4/1969 Lenoir ..260/438.l X 2,381,952 8/1945Gubelmann ..260/438.l X

FOREIGN PATENTS OR APPLICATIONS 1,122,938 8/1968 Great Britain ..I06/288Q 1,123,859 8/1968 Great Britain 106/288 Q Primary Examiner-Tobias E.Levow Assistant Examiner-H. M. S. Sneed AttorneyWenderoth, Lind & Ponack[57] ABSTRACT 17 Claims, No Drawings AZOMETHINE PIGMENTS DETAILEDDESCRIPTION The present invention relates to substituted azomethinecompounds having valuable pigmentary properties. The present inventionrelates in particular to azomethine coloring matters suitable for thepigmentation of paints, lacquers, printing inks, rubber, artificialpolymeric materials, paper and textile materials or other materials, andto processes of producing these azomethine substances.

It is known from U.S. Pat. specification No. 2,166,913 that an oliveazomethine pigment dye may be obtained by reaction ofortho-hydroxybenzaldehyde with ortho-aminophenol and copper acetate.This dye may be converted by certain finishing methods into a form inwhich it can be used in the pigment industry, for instance by grindingwith salt followed by treatment with solvent, but the resulting pigmenthas inferior properties, in particular lacking color strength andstability to acids.

We have found that novel azomethine compounds as hereinafter described,when used as pigments, have greatly improved pigmentary properties interms of good color strength and acid stability combined with excellentfastness properties, particularly to weathering, in finishes ofindustrial importance.

According to the present invention, there is provided a substitutedazomethine compound having the formuwherein X, Y and Z representshydrogen, and/or nitro, amido, carbamoyl substituted by aryl, such asphenyl, arylsulphonyl, such as phenylsulfonyl, alkyl or alkoxy havingone to four carbon atoms or alkyl sulfamoyl wherein each each alkylgroup has one to four carbon atoms, with the proviso that at least oneof the groups X, Y and Z is different from hydrogen. I

If the substitution represented by X, Y and/or Z comprises halogen, thehalogen is preferably chlorine or bromine, and if it comprises alkyl oralkyl sulfamoyl, each alkyl moiety of the substitution is preferablymethyl.

Preferred compounds of the present invention are compounds of Formula Iin which Y and Z represent hydrogen. Especially preferred compounds haveFormula l in which X represents a chlorine atom or a nitro group, asthey are or can provide pigments having particularly useful shadeshaving optimal fastness properties, especially fastness tocrosslacquering, light and solvents.

The present invention also provides a process of producing a compound offormula I which comprises reacting a Schiffs base having the formula:

g Z OH HO (H) with a coppering agent, wherein X, Y and Z have theprevious significance.

The coppering agent may be a conventional agent used in the productionof copperized compounds, and is conveniently a solution of a cupricsalt, for example Copper (II) acetate. The reaction maybe carried outunder a wide variety of reaction conditions, but conveniently theSchiffs base of formula II is heated with the copperizing agent at atemperature within the range of from ambient to 150 C., an elevatedtemperature within the range of from to C. being particularly preferred.The reaction may be carried out in an organic solvent which issubstantially inert under the conditions of the reaction, for instanceformamide, dimethyl formamide, N-methylpyrrolidine, glycol monomethylether, isobutanol or glacial acetic acid. Conveniently the solvent usedis the same solvent employed to form a solution of the cupric saltcoppering agent.

If desired, the Schiffs base of formula II may be prepared during thecourse of the process by the reaction of the orthohydroxy-aldehydehaving the formula:-

with an ortho-aminophenol having the formula:

HQN X HO 2 (IV) wherein X,Y and Z have their previous significance.

Examples of orthoaminophenols which may be used to produce products ofespecial value as pigments are 4- nitro-2-aminophenol,4-chloro-2-aminophenol, 3- amino-4-hydroxy-benzanilide and4-chloro-5-nitro-2- aminophenol.

As a further variation of the process of the present invention, thedesired azomethine compound of formula I may be produced under aqueousconditions in the absence of an organic solvent by reacting an alkalinesolution of an ortho-aminophenol of formula IV with an alkalinesuspension of the aldehyde of formula III, acidifying the resultantproduct (for example with acetic acid) and adding the coppering agent tothe suspension of the Schiffs base of formula II so formed. If desired,the azomethine suspension may be filtered, the azomethine paste washedand then resuspended before the addition of the coppering agent. Thecoppering agent may be aqueous cupric sulphate solution containingsufficient sodium acetate present in solution to maintain the pH valueabove 3. Alternatively a solution of a cuprammonium salt may be used.Surface active agents may also be used if desired. By this variation ofthe process of the invention colored products may be obtained in afinely divided form which are usable directly as pigments.

The present invention also provides a second process of producing acompound of formula I which comprises reacting an azomethine derivativehaving the formula:

wherein X, Y and Z have their previous significance with at least onemolecular equivalent proportion of a coppering agent.

The process is conveniently effected in the presence of anorganicsolvent which is at least substantially inert under theconditions of the reaction, for instance dimethyl formamide. As thissecond process of the invention entails the splitting of the etherlinkage, a higher reaction temperature is in general required than thatin the first process of the invention. The preferred reactiontemperature is within the range of from 140 to 180 C.

The compounds of formula I have valuable pigmentary properties and may,if desired, be bought into pigmentary form by conventional conditioningmethods. The pigments are distinguished by their high color strength,high resistance to solvents, outstandingly good lightfastness in lacquerprinting and intaglio printing, outstandingly good fastness toover-lacquering, and especially by their excellent resistance toweather- Accordingly, the present invention also provides a process ofproducing a pigment which comprises conditioning a substitutedazomethine compound of formula I. The present invention also comprisespigments so produced, and organic materials colored by the pigments ofthe invention.

The desired azomethine compound of formula I need not be pre-formedbefore the conditioning is carried out; it may be prepared during thecourse of the conditioning procedure. For example, the desiredazomethine compound of formula I may be produced by reacting together anortho-aminophenol of formula IV with the aldehyde of formula III andthen a coppering agent while conditioning is carried out simultaneously,for instance in a horizontally rotating gravity grinder (for example, aball-mill), a grinder operated by a vertically rotating shaft,especially a sand grinder, or in a grinder operated by vibratory actionor by any other comminution method compatible with the presence of thechemical reactants. In this type of conditioning, a water soluble coppersalt such as cupric sulphate, conveniently in the hydrated form, isparticularly suitable as the coppering agent, especially in the presenceof an acid buffer such as sodium acetate. If desired, a surface-activeagent may also be used in these conditioning techniques.

Known conditioning techniques may be used, for example, grinding withcalcium chloride, sodium chloride or other organic or inorganic salt,with or without the addition of dimethylaniline, xylene, or otherorganic solvent; or heating with a high-boiling organic solvent, forinstance, nitrobenzene or a-chloronaphthalene. The compounds of formulaI may also be dispersed in water if desired, for example, by means ofpebble milling in the presence of a surface active agent which may be ofthe anionic, cationic or non-ionic type.

The pigments produced in accordance with this invention may be of ashade ranging from greenish yellow to red brown depending on the natureof the substituted azomethine molecule and on the conditioning techniqueemployed. The pigments of this invention are suitable for use in thepigmentation, by known methods, of high molecular weight hydrophobicorganic material, for instance paints, lacquers, printing inks, rubber,synthetic polymeric materials, paper and textile materials. In general,pigments of this invention exhibit good fastness properties, especiallyto light, heat, cross-lacquering and migration, and resistance toorganic so solvents, such as trichloroethylene, toluene and methyl ethylketone.

The present invention also comprises the coloration of an organicmaterial with a substituted azomethine compound of formula I, togetherwith organic materials when so colored.

The coloration may be carried out, for example, by preparing thesubstituted azomethine compound of formula I in a finely divided stateand incorporating it into the organic material in a conventional manner.The pigment may be prepared in a finely divided state, for instance, bymilling with anhydrous sodium acetate in the presence of a minorproportion of xylene, or by other conventional pigment conditioningprocedure.

The high molecular weight hydrophobic organic material or other organicmaterial to be colored according to the invention may be any polymericor other organic material capable of being pigmented or otherwisecolored. The material may be a natural or synthetic polymer orco-polymer, a coating composition for application to the surface of anarticle, or a printing liquid medium. However, the process of theinvention is applicable with particular advantage to the pigmentation ofnatural 'or synthetic polymers or copolymers, in the form of fibers,films or bulk material; to paints, lacquers and othersurface coatingcompositions, or. to tinting compositions for use in preparing suchcoating compositions; and to printing inks. Examples of polymers orco-polymers which may be pigmented by the process are vinyl chloride oracrylonitrile polymers and copolymers; polyethylene, polypropylene andother polyolefines; polyacrylonitrile, polystyrene and polystyrenecopolymers; and natural and synthetic rubbers.

The present invention is further illustrated by the 'following Examples.Parts and percentages shown therein are expressed by weight.

EXAMPLE 1 51.3 parts of 4-nitro-2-aminophenol, and 57 .3 parts of2-hydroxy-l-naphthaldehyde were refluxed for 1 hour in 400 parts ofdimethyl-formamide. The yellow suspension was allowed to cool for 1 hourand a solution of 66.6 parts of cupric acetate in 600 parts ofdimethylformamide was added. The mixture was again refluxed for 1%hours, and the solid was then filtered off, washed withdimethylformamide and with methanol and dried at 60 C.

In this way there were obtained 107.5 parts of light green metalliccrystals having a melting point of 360 C.

The product had the formula;

yethanol, was treated with 3.39 parts of cupric acetate monohydrate,dissolved in 50 parts of dimethylfonna- N=CH mide and the mixture wasrefluxed for 1 hour. The resulting green crystalline product wasfiltered off, 5 washed with dimethylformamide and ethanol and dried at60 C. to give a 92 percent yield.

0 0 The product may be conditioned as in Example 1,

The product was obtained as a fine powder by ball and had the formulamilling with nine times its weight of a mixture of sodi- 10 um acetateand sodium sulphate. The resulting pigment N=CH was isolated by washlngwith water and was a. fine greenish yellow powder. OQN I Cu EXAMPLE 2 l5 15.4 parts of 2-amino-4-nitrophenol and 17.2 parts By substituting anequivalent amount of the apof 2-hydroxy-l-naphthaldehyde were refluxedin 150 propriate aminophenol for the 4-nitro-2-aminophenol parts of2-methoxyethanol for 2 hours. After cooling used in Examples 1 and 2 thecompounds in the followdull-orange crystals (m.pt. 29930l C.) werefiltered ing Table were obtained. The Table also gives the color off,washed with ethanol and dried at 60 C. 4.62 parts 20 in lacquer and asummary of the fastness properties of of this product, dissolved in 50parts of Z-methoxthe pigments.

Example Amlnophenol Product Colourin Lacquer Stability 3 Brownish yell0wGood.

O;N NH;

@015: N=CH l I om 01 4 Orange red Excellent.

Cl NH: I I OzN- OH N=CH Q/ 5 do Very good.

H3C- NH; 1 I

OH N=CH I H30 N02 I O 0 N01 6 Brownish yellow Excellent.

. H:C NH: I

OH N=CH Hm i O O 7 Greenish yellow... Do.

CaH SO NH I OH N=CH CoH5SO2- 8 do D0.

N=CH I 0.1191300 C l Example Aminophenol Product Ldbg ii or Stability mX; Golden yellow" Excellent.

I: -')II N CH 10.. do D0.

N l I; y ()H N=CH i I O 01 11 01 do Very good.

' C1 C1-- NHg N-=CH OH C1 Cl EXAMPLE 12 parts of 2-methoxyethanol for 2hours. After cooling Br I N=CH x Br u The product was obtained as a finepowder powder by ball-milling with nine times its weight of sodiumacetate and sodium sulphate. The resulting pigment was isolated bywashing with water, and was a fine greenish yellow powder.

EXAMPLE 13 50.4 parts of 2-amino-4-nitro anisole and 51.6 parts of2-hydroxy-l-naphthaldehyde were refluxed in 450 yellow crystals (m.pt.22l C) were filtered off,

washed with ethanol and dried at C in 97.5 percent The product may beconditioned as in Example 1, and had the formula:

N=CH O2N l By substituting an equivalent amount of. the appropriateamino-anisole for the 4-nitro-2-aminoanisole used in Example 13 or. the2-amino-3,5,6- tribromo-anisole used in Example 12, the products in thefollowing Table were obtained. The Table also gives the color in lacquerand a summary of the fastness property of the pigments.

(olonr in Example Ammophmwl Product lacquer Stability 1t I5r I/ I- \:HZYellow. (100d.

1 :I l /'--ocm 11?. (1 ll; Greenish D0.

yellow. I

N=CH 2 )2NSO 1 Cu S O2 (C2 5)2 1s 00H; Yellow Do.

NH I

N=CH HzNCO \b NH i 00 EXAMPLE 17 EXAMPLE 19 15.4 parts of4-nitro-2-aminophenol, 17.2 parts of 2- hydroxy-l-naphthaldehyde, and100 parts of water were stirred for 5 minutes before the addition of 4.2parts of sodium hydroxide, dissolved in 50 parts of water, followed byl5.6 parts of sodium bisulphite. The suspension was then heated to 90 C.with stirring for minutes and filtered and the product obtained washedwith 500 parts of cold water. The yellow presscake was stirred into 200parts of water with high speed shear agitation, and to this slurry wasadded a solution of cuprammonium phate p n req..by i solxin 27.5 partsof hydrated copper sulphate in 100 parts of water, and adding 53 partsof concentrated ammonium hydroxide solution to dissolve the initialprecipitate. The slurry was heated to 95 C. for 60 minutes to give adull yellow slurry which was filtered hot, and the product obtainedwashed with hot water and dried at 70 C. Thus were obtained 32.0 partsof dull yellow powder which did not melt below 360 C.

EXAMPLE 18 14.35 parts of 4-chloro-2-aminophenol, 17.2 parts of2-hydroxy-l-naphthaldehyde and 100 parts of water were stirred for 5minutes before the addition of 4.2 parts of sodium hydroxide dissolvedin 50 parts of water, followed by 15.6 parts of sodium bisulphite. Thesuspension was then heated to 90 C. for 15 minutes, filtered and theproduct washed with 500 parts of water. The yellow presscake was stirredinto 200 parts of water with high speed shear agitation and parts ofsodium acetate trihydrate dissolved in 100 parts of water were added.After 15 minutes stirring a solution of 27.5 parts of hydrated coppersulphate in 75 parts of water was added and the slurry heated to 90 C.for 60 minutes. The mixture was then filtered hot, the product washedwith 8,000 parts of hot water and dried. Thus were obtained 38.6 partsof yellow-brown powder, which did not melt below 360 C.

A mixture of 14.2 parts of 4-chloro-2-aminophenol, 17.2 parts of2-hydroxy-l-naphthaldehyde, 200 parts water and 200 parts ceramic balls(half-inch diameter) was placed in'a pot mill and ground for 24 hours.To the ground mixture were added 27.2 parts of sodium acetatetrihydrate, 26 parts cupric sulphate pentahydrate, both as solids andparts of water. Grinding was then continued for a further period of 90hours.

The ceramic balls were then separated off by a coarse mesh sieve and theremainder of the mixture was filtered, and the product washed with waterand dried at 60 C. The resulting pigment was a yellowish brown powdermelting point above 360 C.

The product had the formula:

methoxy ethanol. The lacquers were then prepared in the conventionalmanner and a film of each sample was applied to cardboard. The stovingtime was 30 minutes at C.

The pigmentations made were: a 3 percent mixture comprising 03 parts ofthe pigment in 10 parts of the ll V total mixture and a tint shadereduced 1:100 with titanium dioxide. The overlacquering fastness wasmeasured by overlacquering the film on cardboard with white lacquercontaining 20 percent titanium dioxide and re-stoving at 120 C. for 30minutes. The resultant staining of the white film was then assessed.Heat stability was assessed after re-stoving samples of the lacquerfilms at 120 C. for 30 minutes and at 180 C. for 15 minutes. Thelightfastness was assessed after exposure to a xenon arc lamp bycomparison with the Blue Wool Scale [British Standard 1006( 1961)]. Thelightfastness,.heat stability and overlacquering fastness were all foundto be excellent.

EXAMPLE 21 The dihydroxy azomethine copper [1 complex prepared inExample 17 was incorporated into an emulsion paint.

A paste was formed consisting of 20 parts of the pigment, 80 parts ofwater and 2.5 parts of the sodium dinaphthylmethane disulphonate soldunder the Trade Mark Belloid SFD and milled for 48 hours with 60 partsof coarse quartz sand. The sand was removed by sieving. 0.3 parts ofthis paste were mixed with 30 parts of polyvinylacetate emulsion andstirred until a homogeneous mixture was obtained, and a film of thesample was applied to cardboard. A bright yellow pigmentation withexcellent properties was obtained.

EXAMPLE 22 15 parts of the product of Example 1.0 were stirred into 500parts of dimethylformamide until a smooth ,dispersion was obtained. Thisdispersion was diluted EXAMPLE 23 Various of the copper complexes of theinvention were prepared in a finely divided state by milling withanhydrous sodium acetate and sodium sulphate in the presence of xylene.The product of Example 17 when prepared in a finely divided state asdescribed above was suitable for incorporation into polyvinylchloridefilms of the following formulation:

100 parts of Geon 121 polyvinylchloride 60 parts of dialphenylphthalate3 parts of Advastab B.C. 247 (Ba/Ca salt of long chain fatty acid) 1part of Advaplast 39 (an epoxy soya bean oily condensate (Geon, Advastaband Advaplast are registered Trade MarksfThe dialphenylphthalate is thediester from phthalic acid and the commercially available mixwe oalcohols no n a ,flp nq jl,

Two pigmentations were made, one as a full-shade pigmentation using 1percent of pigment based on the polyvinylchloride content of theformulation, the other being a shade reduction pigmentation using 0.1percent of the pigment together with 1 percent of titanium dioxide, bothpercentages being based on the polyvinylchloride content of theformulation. The films were prepared and cured in the conventional way,the normal film thickness in each case being 1/50th of an inch andcuring being carried out at 170 C. for minutes. There resulted strongbright yellow films the fullshade being especially highly transparent.These films exhibited very high fastness properties for instance tolight and to migration. 15 mm m 1.; A compound of the Formula Cu my a vwhere n X represents from one to three substituent groups which are thesame of different and each is a halogen atom or a nitro, amido,arylcarbamoyl, arylsulphonyl, alkoxyor alkyl group. 2. The compound asclaimed in claim 1 wherein X is a chlorine atom or a nitro group.

3. The copper complex compound having the formu- .l

N=CH OQN K 0 4. The copper complex compound having the formula I ,7 N,V.

Cu \p/ wherein X has the same meaning as in claim 18, with anorthohydroxy aldehyde of the formula CH=O and reacting the resultantproduct with a coppering agent, fine division of the compound of formulaI being carried out simultaneously with its production.

8. A process for the production of a compound according to claim 1 inpigmentary form which comprises reacting, under aqueous conditions inthe absence of an organic solvent, an alkaline solution of a compound ofthe formula HzN- wherein X is as defined in claim 1 with an alkalinesuspension of a compound of the formula CHO acidifying the resultantproduct and adding to the acidified product a coppering agent.

9. A process for the production of a compound according to claim 1 whichcomprises reacting a compound of the formula halogen, nitro, amido,phenylcarbamoyl, phenylsulphonyl, alkoxy of one to four carbon atoms oralkyl of one to four carbon atoms.

13. The process according to claim 12, wherein the halogen group ischlorine or bromine.

14. The compound according to claim 1, wherein X is halogen, nitro,amido, phenylcarbamoyl, phenylsulphonyl, alkoxy of one to four carbonatoms or alkyl of one to four carbon atoms.

15. The compound according to claim 14, wherein the halogen group ischlorine or bromine.

16. The process as claimed in claim 8 wherein the coppering agent is anaqueous cupric sulphate solution containing sufficient sodium acetatepresent in solution to maintain the pH value above 3.

17. The process as claimed in claim 8 wherein the coppering agent is asolution of a cuprammonium salt.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No-3,700,709 Dated October 24 1972 Inventor(s) ERIC RICHARD INMAN, IANALEXANDER MACPHERSON and JOHN ANDREW STIRLING It is certified that errorappears in the above-identified patent and that said Letters Patent arehereby corrected as shown below:

-Foreign Application Priority Data May 23, 1969 GreatBritain.......26504/69 should appear somewhere in the heading of theTitle page.

Signed and sealed this 5rd day of April 1973.

(SEAL) Attest:

EDWARD M.FLETCHER,JR. ROBERT GOTTSCHALK Attesting Officer Commissionerof Patents FORM PO-105O (10-69) USCOMM-DC 6O376-P69 U.S. GOVERNMENTPRINTING OFFICE: [969 0-366-334

2. The compound as claimed in claim 1 wherein X is a chlorine atom or anitro group.
 3. The copper complex compound having the formula
 4. Thecopper complex compound having the formula
 5. A process of producing apigment comprising finely dividing a compound of formula I as defined inclaim
 1. 6. A process as claimed in claim 5 wherein the fine division iseffected in a horizontally rotating gravity grinder, a grinder operatedby a vertically rotating shaft or a grinder operated by vibratoryaction.
 7. A process as claimed in claim 5 wherein the compound offormula I is produced by reacting an ortho-aminophenol of the formulawherein X has the same meaning as in claim 18, with an orthohydroxyaldehyde of the formula
 8. A process for the production of a compoundaccording to claim 1 in pigmentary form which comprises reacting, underaqueous conditions in the absence of an organic solvent, an alkalinesolution of a compound of the formula wherein X is as defined in claim 1with an alkaline suspension of a compound of the formula
 9. A processfor the production of a compound according to claim 1 which comprisesreacting a compound of the formula
 10. The process according to claim 8,wherein X is halogen, nitro, amido, phenylcarbamoyl, phenylsulphonyl,alkoxy of one to four carbon atoms or alkyl of one to four carbon atoms.11. The process according to claim 10, wherein the halogen group ischlorine or bromine.
 12. The process according to claim 9, wherein X ishalogen, nitro, amido, phenylcarbamoyl, phenylsulphonyl, alkoxy of oneto four carbon atoms or alkyl of one to four carbon atoms.
 13. Theprocess according to claim 12, wherein the halogen group is chlorine orbromine.
 14. The compound according to claim 1, wherein X is halogen,nitro, amido, phenylcarbamoyl, phenylsulphonyl, alkoxy of one to fourcarbon atoms or alkyl of one to four carbon atoms.
 15. The compoundaccording to claim 14, wherein the halogen group is chlorine or bromine.16. The process as claimed in claim 8 wherein the coppering agent is anaqueous cupric sulphate solution containing sufficient sodium acetatepresent in solution to maintain the pH value above
 3. 17. The process asclaimed in claim 8 wherein the coppering agent is a solution of acuprammonium salt.